Speaking in a video released to thank their European fans for support during their recent tour, the guitarist says: "This band is really picking up steam now - there's something in the air."

While his bandmates make equally positive-sounding comments without committing to anything, Richards adds: "Our strength lies in being together. There's a certain chemistry. I can't put my finger on it - if I knew the answer I'd bottle it and sell it.

"It's been a real buzz. I think I may keep this job on."